Profile: Hunan Great Steel Pipe Co., Ltd. is a supplier of seamless steel pipes, ERW, SSAW, and LSAW pipes. Welded steel pipes are used for low pressure liquid delivery such as water, gas, and oil. SY/T5037 spiral submerged arc-welded steel pipes are used for pipelines for low pressure field fluid service. CJ/T 3022 spiral submerged-arc welded steel pipes are applied in municipal heat supply. Mechanical seamless steel tubing is applicable to the general structure & mechanical structure with seamless steel tubes. Casing is a large-diameter pipe that serves as the structural retainer for the walls of oil & gas wells, or well bore. It is inserted into a well bore, and cemented in place to protect both sub-surface formations & the well bore from collapsing, to allow drilling fluid to circulate, and extraction to take place. Steel casing pipes have smooth walls & minimum yield strength of 35,000 psi. Tubing is used for the transportation of crude oil and natural gas from an oil or gas layer to the surface after drilling is complete. It is made to withstand the pressure generated from the extraction process. Tubing is manufactured in the same way as casing, except that an additional process known as upsetting is applied to thicken the pipes.